000
AXPZ20 KNHC 271539
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN SEP 27 2009

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN
FROM THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1530 UTC.

...ITCZ...
AXIS IS ALONG 09N80W TO 07N89W TO 12N96W TO 12N103W TO 09N109W 
TO 10N115W TO 17N128W TO 13N140W. SCATTERED MODERATE TO STRONG 
CONVECTION WAS FROM 05N TO 10N E OF 93W.  ISOLATED MODERATE 
CONVECTION WAS WITHIN 180 NM EITHER SIDE OF AXIS W OF 113W.

...DISCUSSION...

W OF 100W...
LARGE E-W ELONGATED UPPER LEVEL CYCLONIC CIRCULATION CENTERED 
JUST NW OF THE AREA NEAR 30N142W WITH ASSOCIATED CYCLONIC FLOW N 
OF 20N W OF 120W. AN AREA OF MID LEVEL MOISTURE WITH ISOLATED 
EMBEDDED SHOWERS WAS NOTED FROM 26N-32N BETWEEN 127W-133W...
ROTATING AROUND THE EAST SIDE OF THE CYCLONIC CIRCULATION. AN 
AREA OF MODERATE TO STRONG SUBSIDENCE WITH DRY STABLE AIR AT THE 
MID TO UPPER LEVELS WAS NOTED FROM 20N TO 30N W OF 128W AND WAS 
SWEEPING EASTWARD INTO THE AREA OF MOISTURE NOTED ABOVE. 
AXIS OF SUBTROPICAL JET EXTENDED THROUGH 18N140W TO 24N127W
AND WAS SLICING ACROSS THE SOUTHERN EXTENT OF THE AREA OF DRY 
AIR. SATELLITE DERIVED WINDS WERE IN THE 60-80 KT RANGE. 

AN UPPER LEVEL RIDGE IS LOCATED S OF THE CYCLONIC CIRCULATION 
EXTENDING FROM AN ANTICYCLONIC CIRCULATION NEAR 24N112W THROUGH 
18N125W TO 12N135W. ANOTHER RIDGE EXTENDS EASTWARD ALONG 22N 
FROM THE ANTICYCLONIC CIRCULATION ACROSS NORTHERN MEXICO. 
DRY AIR AT THE MID AND UPPER LEVELS ACCOMPANIED THE ANTICYCLONE 
WHILE DIFFLUENT NE TO E FLOW WAS NOTED SOUTH OF THE ANTICYCLONE.
THIS FLOW WAS SUPPORTING AREAS OF SCATTERED MODERATE TO STRONG 
CONVECTION FROM THE ITCZ NORTHWARD TO THE MEXICAN COAST BETWEEN 
93W AND 110W.

AT THE SURFACE...HIGH PRES RIDGE IS N OF 20N W OF 115W. THE 
REMNANT LOW OF NORA...1008 MB...CENTERED NEAR 18N128W AND IS 
EXPECTED TO DISSIPATE WITHIN THE NEXT 24 HOURS. THERE IS NO DEEP 
CONVECTION ASSOCIATED WITH THE LOW. A 1007 MB SURFACE LOW IS 
ANALYZED ALONG THE ITCZ NEAR 12N117W. A SMALL CLUSTER OF 
THUNDERSTORMS WAS ASSOCIATED WITH THIS AREA OF LOW PRESSURE. 

E OF 100W...
AN UPPER LEVEL CYCLONIC CIRCULATION IS CENTERED OVER GUATEMALA
AND IS MOVING INTO MEXICO TOWARD THE ISTHMUS OF TEHUANTEPEC.  
UPPER LEVEL DIFFLUENT FLOW BETWEEN THIS CIRCULATION AND THE 
ANTICYCLONE NEAR 24N112W IS ENHANCING CONVECTIVE ACTIVITY S OF 
THE GULF OF TEHUANTEPEC AND ALSO ALONG THE ITCZ E OF 92W. 

A SURFACE TROUGH WAS NOTED ALONG THE ITCZ FROM 9N TO THE COAST 
OF MEXICO ALONG 97W/98W. 

$$
COBB